1. Field of the Invention
The present invention relates to a crane, and in particular to a pin structure of a crane with an automatic counterweight balancing device and a method of arranging counterweight thereof.
2. The Related Arts
Liquid crystal display (LCD) has a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and is thus widely used. Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise a liquid crystal display panel and a backlight module. The operation principle of the liquid crystal display panel is that liquid crystal polymer molecules are interposed between two parallel glass substrates and the liquid crystal molecules are controlled to change direction by application of electricity to the glass substrates in order to refract out light emitting from the backlight module for generating images.
A liquid crystal display panel is generally composed of an upper substrate (CF, Color Filter), a lower substrate (TFT, Thin Film Transistor), and liquid crystal (LC) interposed between the upper substrate and the lower substrate, and a sealant. A general manufacturing process comprises a front stage of array process (including thin film, yellow light, etching, and film stripping), an intermediate stage of cell process (including bonding TFT substrate and the CF substrate), and a rear stage of assembling process (including mounting drive ICs and printed circuit board). The front stage of array process generally makes the TFT substrate for controlling the movement of liquid crystal molecules. The intermediate stage of cell process generally introduces liquid crystal between the TFT substrate and the CF substrate. The rear stage of assembling process generally mounts the drive ICs and combining the printed circuit board to effect driving the liquid crystal molecules to rotate for displaying images.
In the manufacturing process and warehousing of the liquid crystal display panel, the liquid crystal display panel is conveyed very often. To save the time of conveyance, the conventional way of conveying the liquid crystal display panel is generally carried out with a crane (as shown in FIG. 1) in order to realize conveyance of cassette (CST). In other words, a carriage platform 100 of a crane is loaded with cassettes of liquid crystal display panel 300 stacked thereon. Generally, a cassette of liquid crystal display panel 300 is of a weight of 2 tons. Motors 500 for Z-axis of the crane must carry quite a load. This may shorten the lifespan of the crane and thus increases the manufacturing cost.
To cope with the above problem, those skilled in the related art attempts to reduce the loading of the motors in the Z-axis of the crane by adopting a solution of increasing the counterweight of the crane. However, the counterweight is only used to balance the weight of Z-axis mechanisms. When cassettes are loaded on the carriage platform, the motors of the Z-axis are also carrying a great load and thus, the above descried issue cannot be well dissolved.